Synthetic detergent formulations containing n-acyl taurates



SYNTHETIC DETERGENT FORMULATIONS CONTAINING N-ACYL TAURATES Richard D. Stayner, Berkeley, and Henry Y. Lew, San

Francisco, Calif., assignors to California Research Corporation, San Francisco, Calif., a corporation of Delaware No Drawing. Application December 16, 1954 Serial No. 475,815 2 Claims. (Cl. 252-152) theticf' detergents, when employed in non-automatic and United States Patent automatic agitator-type washing machines, although elfi- Y ,cient insofar as their detersive or cleansing action is concerned,.are unsatisfactory with respect to their foam performance: (1) they produce very little foam'in the presence of soil; (2.) their foams usually have a lacy texture; and (3) during the agitation of the contents of the tub of. a washing machine the foam readily collapses and disappears. V

It is generally extremely diflicult, if not impossible, to predictthe foam characteristics of an anionic synthetic detergent containing, inaddition to a sulfate or a sulfonate group, an intermediate linkage, e.g., an ester, an ether, for anamide linkage In, addition, one cannot be certain that a compound capable of improving the foam performance of a particular group of anionicfo'rganic sulfate or sulfonate detergents willsimilarlyinfluence the foam performance of a different group of anionic sulfate or sulfohate detergents containing an, additional orfa different intermediate linkage. Thus, formulation of synthetic anionic detergent compositions possessing a high degree of washingefliciency and simultaneously capableof foam performance equivalent to that of the better household laundry soaps constitutes a diflicult problem. a, Water-soluble N-acylaminoalkanesulfonates or N-acyl taurates of the formula: 1 g

R-CO-N(R) (CH '),SO M wherein R may be a long alkyl chain. containing from "9 to 17 carbon atoms, R maybe hydrogen or a methyl ra dic'al, x may be an integer from 2 to 4, and M may be analkali metal or ammonium cation, have been known in the art as effective anionic detergents, stable in aqueous acid and alkaline solutions. Preparation of N acylaminoalkanesulfonates has been described in the art. The conventional procedure for the preparation of these N-acyl taurates, for example, in- .volves reaction of an acyl chloride, e.g., oleoyl chloride .orlauroylchloride, with taurine or N-methyl taurine, followed by neutralization of the resulting N-acyl taurine, e.g., with sodium hydroxide, to yield the desired taurate. Owing to the abundant supplies of tallow on the market, large quantities of inexpensive 0 -0 saturated fatty acids can be made available for the manufacture of detergent N-acyl taurates. However, when these acids produced by hydrolysis of tallow and hydrogenation are employed to make N-acyl taurates, dilute aqueous solutions of detergent compositions formulated with these :taurates, when agitated in the presence of soil, fail to produce a satisfactory stable foam. The resulting suds {are lacy, in texture, greyish in colorand relatively low in .collapse and disappear.

R 2,921,030 Patented Jan. 12, 1969 ice insufficient volume and poor stability, do not persist, but This lack of foam persistence results in decreasing the demand for detergent compositions containing N-acyl taurates derived from hydrogenated tallow fatty acids by the foam-conscious consumer who considers the persistence of foam to be a criterion of washing efficiency.

We have found that synthetic detergent compositions containing as their active organic detergent component a water-soluble N-acyl taurate of the aforedescribed type, when dissolved in water in concentrations from 0.1 to 0.4% such as are commonly employed in laundry practice, may be rendered capable of producing an adequate volume of stable, good-quality suds, persistent under the conditions of agitation in the presence of soil, by incorporating into these detergent compositions an effective proportion of certain para-substituted phenols or their lower molecular weight alkylene (ethylene and propylene) glycol ethers as foam-improving additives. Y

The para-substituted phenols suitable for the purpose are those in which the para-substituents attached to the benzene nucleus in the position para to the hydroxyl group are members of the group consisting of straight-chain C -C alkyl radicals and straight-chain C -C acyl radicals. 7 V

' These para-substituted phenols operative in accordance with our invention thus include among the para-acyl phenols, p-decanoyl phenol, p-lauroyl phenol, p-myristoyl phenol, while among the para-n-alkyl phenolsmay be named p-n-decyl phenol, p-n-dodecyl phenol and p-nthe p-acyl and p-n-alkyl phenols, which may be also designated as hydroxyalkyl ethers of these phenols, are those containing from 1 to 2 oxyethylerie or oxypropylene units in the glycol portion thereof and include in their number monoethylene' glycolethers, diethylene glycol (ethers and monopropylene glycol ethers, the monoethyl- 'ene glycol ethers being preferred. The amounts of the para-substituted phenols or their lower molecular weight yolnme. ;In thecourse of agitation in contact with soiled I glycol ethers effective in improving the foam performance .of synthetic detergent compositions containing water- .soluble N-acyl taurates may range from about 1% to about 5%, based on the total weightof the detergent composition. These phenols and glycol ethers thereof can be prepared in any suitable manner disclosed in the art; I

A portion of the active N-acyl taurates derived from hydrogenated tallow in the detergent compositions of the present invention may be replaced by the well-known C C monoalkyl benzene sulfonates, in proportions not exceeding 95 by weight of the total'active organic component, thereby increasing the volume of foam that can .be produced by the dilute aqueous wash solutionsof these compositions, without interfering with the effect of para-substituted straight-chain C -C 4 alkyl and C C acyl phenols .or of their corresponding low molecular weight glycol ethers on the stability and persistence of the foam, as hereinbefore described.

While detergent C C monoalkyl benzene sulfonates may constltute as much as 95% by weight of the organic detergent component in the compositions of our invention, replacing a portion of N-acyl taurates, amounts equal to 85% and less are preferred, those from to 50%, based on .the weight of the total organic detergent component of the formulation, being most effective. In somecases less than 50% of the sulfonate may be employed as a replacement of N-acyl taurate. The quantity of para-substituted phenol or its glycol ether efiec' tive in providing the desired degree of foam persistence and stability under agitation in the presence of soil, may range from 1% to 5%, based on the total weight of the detergent composition.

The use of monoalkyl benzene sulfonates substantially reduces the costs of formulating. 'The preparation of these detergent sulfonates is known in the art and is de- -scribed, e.g., in US. Patent No. 2,477,383 to Lewis an .U.S. Patent No. 2,218,472 to Kyrides.

The excellent foam properties of the detergent compo- ;sitions of the invention are not affected adversely by the presence therein of inorganic salt builders commonly em- :PlOYCd in anionic detergents, and particularly in the so- ,called heavy-duty detergents. These builders are neutral salts of strong inorganic acids (chlorides or sulfates), and alkaline'salts of weak inorganic'acids (carbonates, .phosphates, borates, etc.). We have foundthat the improved detergent compositions of this invention, in ad- ,dition to N-acyl taurates as the active component (either with or without admixture of monoalkyl benzene. sulfonates) and in addition to the para-substituted phenol ;or a glycol ether thereof as the foam-improving agent, may contain in each 100 parts'by weight, based on the total content of solids in the detergent formulation, from 60, to 90 parts by weight of the aforesaid water-soluble inorganic builders, sodium salts being usually preferred. These sodium salts include sodium carbonate, sodium ;tripolyphosphate, tetrasodium pyrophosphate, sodium chloride, borax, etc.

Well-known fatty acid alkylolamide foam improvers such as lauric isopropanolamide'and lauric ethanolamide may be added, if desired, to the detergent compositionof the invention to improve the tolerance of soil by the foam in small amounts, conventionally employed in the art, .without interfering in any manner with the beneficial effect of the para-substituted phenols or their glycol ethers on foam persistence under the conditions of agitation.

Furthermore, if so desired, other conventional additives, such as anti-caking agents, optical bleaches, corrosion inhibitors, perfumes and dyes, may be present in the detergent compositions. Carboxymethyl cellulose or cel- -luronic acid salts may be introduced to prevent redeposition of the soil, and N-alkyl glycines and diglycines may likewise be added to prevent occurrence of skin rashes and .erythemas. All of the aforesaid additives are usually employed in small amounts, usually less than 5% by :weight, based on the total content of solids in the composition, and in all events in such amounts as not to interfere with the improvement in foam performance in accordance with the invention.

The various ingredients of my detergent compositions can be blended by dissolving them in water to form a slurry, and subsequently drying the homogenized blend .to a solid particle form; or evaporating it to form a paste; or diluting it to give a liquid concentrate.

Ordinarily laundry operators and housewives resort to the use of a bleach, such as a hypochlorite, to remove strains from white fabrics, adding this bleach to the washing solution at the completion of the washing cycle and prior to the rinse, or during the rinse. However, many housewives prefer to add the bleach to the wash water simultaneously with the detergent before the start of the washing cycle or during it. In such a case, if the foam; improving additive is a para-substituted phenol (acyl phenol or n-alkyl phenol), the bleach is observed to impair the foam performance, i.e., stability and persistence, notwithstanding the presence of the phenol additive. Both para-acyl phenols and particularly para-n-alkyl phenols are observed to be vulnerable to the action of the bleach. Therefore, whenever bleach is to be added simultaneously with the detergent or at any time during the washing cycle, we recommend employment of lower molecular weight glycol ethers of para-substituted phenols in accordance with the invention, particularly of para-acyl phenyl glycol ethers. When these para-acyl phenyl gly- 2,921,030 r w a 7 col ethers are introduced into a detergent composition in which the active organic component is N-acyl taurate (a portion of which not to exceed may have been substituted by detergent alkyl benzene sulfonate) in amounts from 1 to 5% based on the total weight of the detergent composition, dilute aqueous wash solutions of such a composition produce copious suds of good quality, which persist throughout the washing cycle under agitation in the presence of soil, notwithstanding the presence of the hypochlorite bleach.

Glycol ethers of para-n-alkyl phenols of a similar structure, except for having attached a straight C -C alkyl chain to the aromatic nucleus instead of the C -C acyl group, display a like ability to stabilize the foam of aqueous dilute solutions of detergent compositions based on N-acyl taurates or mixtures of N-acyl taurates and alkyl benzene sulfonates as the active organic components thereof, despite the presence of conventional hypochlorite bleaches therein, though somewhat less effectively than the glycol ethers of para-acyl phenols.

Foam evaluation bench tests were carried out at the laboratory using aqueous wash solutions of the detergent compositions prepared in accordance with the invention. In a representative test series, each parts by weight of the solid detergent formulation contained from 20 to '22 parts by weight of a combination of the following organic ingredients: active N-acyl taurate, active monoalkyl benzene sulfonate and a para-substituted phenol '(n-alkyl or n-acyl) or its lower molecular weight glycol ether in the proportions within the ranges hereinbefore specified. Sodium C -C polypropylene benzene sulfonate was employed as a typical monoalkyl benzene sulfonate. The taurate component was N-acyl-N-methyl taurate derived from hydrogenated tallow fatty acids. In several tests the acyl group was derived from oleic acid to permit comparison of the foam performance of the corresponding N-oleoyl-N-methyl taurate with that of the taurate derived from hydrogenated tallow fatty acids. Para-lauroyl phenol was employed as typifying the para-acyl phenols, p-n-dodecyl phenol as typifying the para-n-alkyl phenols, and monoethylene glycol ether of p-lauroyl .phenol as exemplifying the effective glycol ethers.

Inorganic builders and additives were present in the following amounts: 30 parts by weight of sodium tripolyphosphate; 20 parts by weight of tetrasodium pyrophosphate; 5 parts by weight of liquid sodium silicate as a corrosion inhibitor; and theremainder to make 100 parts by weight sodium sulfate. Sodium silicate had a bla ozsio ratio of 1:32. The detergent product was dissolved in soft water from the laboratory tap (50 p.p.m. of CaMg hardness) at F. to make up 500 ml. of a 0.15% solution in a 2 liter breaker. Water hardness is represented here in parts per million of calcium and magnesium calculated as CaCO and MgCO in a weight ratio of 2:1. The solutions were then tested at the bench by agitating the contents of the beaker'with the aid of a propeller-type stirrer for one minute. The contents were then allowed to stand for one minute, and foam heights in mm. were determined. In another 15 minutes after the termination of the agitation, the foam heights .were measured again. Stability of the foam was rated by observing the rate of foam decay under mechanical stress, as by blowing on a small volume of foam gently with air. When the foam withstands being blown upon, its stability is Good. An unstable foam rapidly collapses when blown upon; its stability is rated to be Poor. Intermediate stabilities are rated as Fair. Foam of Good quality is made up of uniformly smallsized, dense-bodied bubbles of high bulk viscosity. It is white and opaque. Foam of a Poor quality has large-sized bubbles, a low bulk viscosity and tends to be lacy. It is, -furthermore, greyish in color and more 5 transparent: l'tie' foam 'intermedia'te'in' quality between Poor 'and "Good" foam is rated to be Fair. The data fromseveral representative test runs "are tabulated in the table below to illustrate the advantages of the improved composition of our invention.

'6 of f such .N-acyl" taurate," in 'the' absence .:.of' the-"foama stabilizing additives according to the invention, is .low and the quality and stability of the foam are poor (run No. 1). Likewise, replacement of a portion of" the taurate by alkyl benzene sulfonate increases the volume Table l.-Fam evaluation results I 7 Sodium N-aeyl-N-methyl Monoalkyl' Foam Height Test Run taurate -Parts Foam-stabilizing Parts benzene lnmm.aiter- Foam Foam by agent by sulfonate Stability Quality weight weight in parts Acyl group derived fromv by weight 1 min. 15min.

1 A rnirtnreothydrogenated 20 None 0 0 38 29 Peon... Poor. tallow fatty acids. a do 10 ..-.-do 0 10. 62 23 do.. Do. a do -18 p-lauroyl phenol-- 2 0 53 42 Good.-- Good. 4- co. 10 do 2 10 82 64 ..do..-- Do. 5 do 3 -.---d0 2, 17 88 70 d0-- D0. It 0 8 p-n-dodecylphenoL. 2 11 86 67 0.--- Fair. 7 do. 10. 0 2 85 72 0---- Good. n rn 10 Monoethylene gly- 2 v10 f "85 .75 0-..- Do.

, col ether of pz lauroyl phenol. I 9 None. 0 p lauroylphenol 2 20 15 5 Poor..-. Poor. m ()lgicnr irl ....-do 2 0 78 60 F Fair. 11 do 10 0 10 76 58 Poor.- Poor. 19 do. 10 2 10 82 68 Fair.... Fair. 2 do- 2 0 0 68 43 Poor Poor. 14 None 0 0 2o 89 72 .--do..-- Do.

The results in the table clearly demonstrate the superior foam performance of aqueous wash solutions of the de tergent compositions containing active N-acyl taurates derived from hydrogenated tallow fatty acids, when formulated in accordance with the invention.

Compositions containing N-acyl (tallow acid) taurate alone (test run No. 1) produced a low volume of unstable, poor-quality foam. Compositions containing a mixture of N-acyl (tallow acid) taurate and alkyl benzene sulfonate (test run No. 2) in the absence of a foam-improving agent-whether a para-substituted phenol or its glycol ether-produced a higher volume of foam which lacked, however, in quality and stability. The foam in each instance is incapable of persistence under agitation in the presence of soil.

As could be expected, when the only organic detergent active in the composition was monoalkyl benzene sulfonate, the foam was unstable, lacy and lacked persistence despite the formation of a considerable volume of suds (run No. 14). Addition of the foam-stabilizing agent, p-lauroyl phenol, not only failed to provide sulficient stability to the foam of the composition containing the sulfonate as the only active, but actually exerted a defoaming efiect (run No. 9). r l y In the test where the formulation contained N-acyl (tallow acid) taurate alone and a para-substituted phenol as the foam-improving agent (run No. 3), the quality and stability appeared to be improved, but the foam volume was inadequately low. In the tests Nos. 4, 5, 6, 7 and 8, where the formulation was based on the mixture of active N-acyl (tallow acid) taurate and monoalkyl benzene sulfonate in accordance with the previous description of the invention, the presence of para-substituted phenols and the lower molecular weight glycol ethers resulted in the formation of a large volume of foam of good stability, suflicient to assure persistence in the tub of a washing machine during the average washing cycle of 20 minutes.

Test runs Nos. l0, 11, 12 and 13 illustrate the difference in the foam behavior of N-acyl taurates in which the acyl group is derived from an unsaturated fatty acid, such as oleic acid. These runs indicate that N-oleoyl taurate responds only slightly to the additions of alkyl benzene sulfonate and of p-lauroyl phenol with respect to the formation of satisfactory, stable foam;

but fails -to secure the desired stability (run No. 2). It is only when the mixture of N-acyl (tallow acid) taurate and alkyl benezene sulfonate is combined with an effective amount of a para-substituted phenol or a lower molecular weight glycol ether thereof'that stability sufficient to secure the most satisfactory persistent suds is achieved.

In testing foam persistence under the condition of agitation in a washing machine, the tub or bowl of the machine was filled with soft water (50 p.p.m.) containing a 0.15 concentration of the detergent formulation to a standardized level and then charged with a load of soiled cotton towels. The 50 p.p.m. figure for water hardness again represented parts per million of calcium and magnesium calculated as their carbonates and in a weight ratio of 2:1. The contents of the tub were agitated in each test under identical conditions and at the same temperature -125 F.).

The results of the washing machine tests confirmed those of the bench tests. substituted phenols or of their corresponding low molecular weight glycol ethers, the suds of wash solutions containing N-acyl (tallow acid) taurates, and mixtures of these taurates with alkyl benzene sulfonates, according to the invention, were of a poor quality and weak texture, and had a small initial volume incapable of persistence through the complete washing cycle in the tub of the machine in the presence of soiled towels. On the contrary, in test runs employing the wash solutions of the detergent formulations of the present invention, copious, good-quality suds were produced in the tub throughout the 20 minute (or longer) cycle of agitation in the presence of soiled towels. In a typical test run where the wash solution corresponded to that of bench test No. 4, the foam layer was higher than three inches and the foam favorably compared with the rich, creamy suds of the conventional laundry soap. Satisfactory foam performance is obtained,-in fact, in either soft (50 p.p.m.) or hard (300 p.p.m.) water solutions which exert a very satisfactory cleansing action, i.e., possess a good detergency when washing soiled clothes, particularly when washing cottons.

Considering the observed deficiencies in the foam performance of detergent N-acyl taurates derived from hydrogenated tallow fatty acids and in view of the known fact of laciness and low static stability of the foam formed by sulfonate-type detergents, it is entirely unexpected to find that the combination of two such detergents with a minor amount of para-substituted phenol or its lower molecular weight glycol ether in accordance In the absence of the parawith the invention; when dissolved-.inwater in 00138811! trations from about 01 to about 0.4%, can produce foam of excellent quality, similar. in texture to' soap;- suds, and of such a volume as' to be capable of per: sistence in the tub of an agitator-type washing machine during a complete washing cycle of 20 or more minutes.

In conclusion, it is to be understood that the invention is not limited to the specific examples submitted in the above specification merely to illustrate the perativeness of our improved detergent compositions;

We claim: V

1. A detergent composition consisting-'essentially'of a water-soluble N-acylaminoalkane sulfonate detergent 'd'erived from C -C hydrogenated tallow fatty acids, a water-soluble C -C3; monoalkyl benzene sulfonate detergent, the former being'present in an amount of about 15% to 50%, by weight and the latter 85% to 50%, by weight, of the total of the two, and, as foam-improv-- ing agent, from about 1%. to 5.%', by weight, based on the total solids content of said detergent composition, of para-n-dodecyl phenol.-

References Cited in the file of this patent UNITED STATES PATENTS 1,932,180 Gunther Oct. 24, 1933 2,075,018 Bruson Mar. 30, 1937 2,088,085 Gross ..-..July 27, 1937 2,125,310 Perkins Aug. 2, 1938 2,213,477 Steindorif Sept. 3, 1940 2,25 ,556 Q m -V---,-- Oc 7, 1.941 2,477,383 Lewis July 26, 1949 2,7 ,0 P ----V--H-- as ,Aug- 1 2,768,-956- Scott Oct. 30, 1956 FOREIGN V PATENTS 7 711,467 Great Britain July 7, 1954 

1. A DETERGENT COMPOSITION CONSISTING ESSENTIALLY OF A WATER-SOLUBLE N-ACYLAMINOALKANE SULFONATE DETERGENT DERIVED FROM C16-C18 HYDROGENATED TALLOW FATTY ACIDS, A WATER-SOLUBLE C9-C18 MONOALKYL BENZENE SULFONATE DETERGENT, THE FORMER BEING PRESENT IN AN AMOUNT OF ABOUT 15% TO 50% BY WEIGHT, AND THE LATTER 85% TO 50%, BY WEIGHT, OF THE TOTAL OF THE TWO, AND AS FOAM-IMPROVING AGENT, FROM ABOUT 1% TO 5%, BY WEIGHT, BASED ON THE TOTAL SOLIDS CONTENT OF SAID DETERGENT COMPOSITION, OF PARA-N-DODECYL PHENOL.
 2. A BUILT DETERGENT COMPOSITION CONSISTING ESSENTIALLY FROM ABOUT 10 TO 40% BY WEIGHT OF THE DETERGENT COMPOSITION DEFINED IN CLAIM 1 AND 90 TO 60% BY WEIGHT OF WATER-SOLUBLE INORGANIC SALT BUILDERS. 